At the time, I thought Muschamp was a good DC for us back in 2003. In retrospect, I'm less inclined to give him credit for that now that I know Saban's DCs were basically interchangeable and the defenses were always really his. But then in Muschamp's first stint with Auburn, I thought he did a very good job as DC. Then came Texas, where I don't remember his defenses as well as the McCoy offenses, but apparently the '09 team had a defense that, at the least, got them to a NC game. The memory is probably sullied by his last year at UT, 2010, I believe, which everything looked like a dumpster fire. In between UF and SCar he was briefly Auburn's DC again, and my memory of that stint is undoubtedly skewed by his defense's performance against us that year, which was abysmal. Fournette ran around, over, under, and through his defense while his line got absolutely mauled, and the worst part of it was (for them, for me it was delicious) they just weren't trying very hard. After a while it became clear the back 7 wanted no part of Fournette and their tackling effort was one of the worst I've ever seen.
Haven't kept up with him since SCar, but his Wiki page says he was co-DC at UGA for some very good years, then appears to have been.....demoted?.....to an analyst for the last two seasons. Kinda weird.
Overall, I think he's shown he's not great at getting more out of less, but that he's pretty lethal when he's got the hosses. Since Texas will have the hosses, I assume he's a good fit there.